ProBioSSep (Microbial processes, stabilization, separation)

Process and bioprocess engineering currently faces major challenges in process intensification. It involves hybrid technologies combining multiple operations within a single piece of equipment, or flexible, low-cost and high-performance series of operations. Our goals are to “produce better, using less”, which means in smaller volumes, with greater efficiency and selectivity, using less energy, water, raw materials and solvents, together with minimizing the environmental impact.

As a relevant strategy to meet these challenges, micro-organisms to carry out chemical and biochemical reactions are used. For upstream and/or downstream stages (essentially separation processes), our optimisation strategies focus on understanding and characterising physicochemical phenomena in complex environments. We also deploy new systemic approaches, based on the integration of production, transformation and stabilisation of renewable materials into foodstuffs and bioproducts, to ensure their functionality during storage. Another challenge is to take into account by-products as raw materials, as well as environmental impacts during the process of designing or (re)designing products and processes.

Research question and scientific expertise

The ProBioSSep team research work is focused on a central question: "How to design and optimize production/stabilization or production/separation processes that integrate product quality, process performance and environmental impact?"

To answer this question, our works are devoted to :

• Implementing microbial processes (fermentation and bioconversion) in order to maximise the expression of biological functionalities and to characterise the biophysical and physiological responses of micro-organisms using a multi-scale approach;
• Studying membrane and chromatographic separation processes, stabilisation processes by freezing, freeze-drying and drying processes, in order to understand and model the mechanisms that govern transfers, with a view to optimising their performance;
• Working on intensification of processes by improving the performance of heat, mass and momentum transfer and reactivity;
• Studying the coupling of unit operations, such as extractive fermentation and cascade membrane processes, while minimising utility consumption (energy, solvents, process water) and, more generally, environmental impact;
• Integrating by-products as raw materials for processing;
• Deploying large-scale optimisation strategies to improve energy efficiency and minimise water consumption.

Our objects of study

We are interested in real and complex media and matrices (i.e., fermentation media, hydrolysates, effluents, agro-industrial by-products), in the products of interest that can be obtained from these various raw materials, such as micro-organisms with interesting functionalities, "platform" molecules, organic acids, flavour compounds…, and in the processes that contribute to their use or production (biotechnological and/or separative processes).

Concerning microbial functionalities, the team’s research explores microorganisms of interest that are implemented in bioreactors to achieve either:

• Microbial biomass under controlled conditions, which can be stabilized by freezing, freeze-drying or drying, and whose performance and functionalities are characterized according to various criteria;

• Molecules of interest produced through bioprocesses, particularly from agro-industrial by-products or effluents, to which unit operations may be applied within coupled or even integrated processes.

Across both of these approaches, the coupling strategy we develop aims to optimize the studied processes by minimizing utilities (energy, water, effluents), notably by using ‘Pinch’ methods for water and by implementing Life Cycle Assessment (LCA) methodologies.

Our research activities in a few key-words

• Microbiological processes: lactic and acetic fermentations, bioconversion; evaluation of cellular state of microorganism; evaluation of biophysical and physiological responses of microorganisms;
• Stabilisation processes: freezing, freeze-drying, air drying, superheated steam drying;
• Separation processes: membrane separation (ultra-filtration, nano-filtration, reverse osmosis, electrodialysis, pervaporation, membrane contactors) ; chromatography (adsorption, ions exchange);
• Process integration : coupling processes and/or bioprocesses; energetic integration; optimisation methods;
• Process intensification: of unit operations, coupled processes, in a factory;
• Evaluation of environnemental impacts.